A super cool phenomenon is happening all over California beaches, and it's one that scientists haven't seen in about a decade: millions of jellyfish-like creatures known as 'valella valella," or "by-the-wind sailors," are washing up on beaches along the coastline, giving the shoreline a unique hue -- and at times, a pretty awful smell.

Still, they're pretty gorgeous, despite the pitfalls of the ocean stench. These Velella velella are a regular thing offshore each spring, where they cluster together annually. But it's really unusual to see so many onshore, especially so late in the summer.

Though not poisonous to most people, beachgoers should avoid the animals because their venom can cause stinging in the eyes and mouth, said Steve Rumrill, an expert at the Oregon Department of Fish and Wildlife.

The creatures are washing ashore from California to Washington by the millions, and ocean experts aren't sure exactly why the by-the-wind sailors are washing up now, so late in the summer.

Climate change may be a factor, or even the unusual winds, according to experts. But ultimately, it's impossible to tell exactly why they're dotting the sea, and the shoreline, with hues of blue and purple. All we know is that they're coming by the droves.

And although most beach-goers will identify the Velella velella as jellyfish by their blue color and clear tops, they are in actuality much smaller creatures known as hydrozoans.

While the creatures look like one organism, the Velella are actually made up of hundreds of tiny organisms that are clustered together to create a bright blue and purple body, and a translucent sail-like protrusion -- hence the name by-the-wind sailors -- that gives the appearance of being a single animal.

They travel by the stiff breeze of the ocean, which may be one reason as to why they're appearing on beaches across the West Coast.

But no matter why they're appearing, one thing is for sure: They make for pretty social media photos. And as with any scientific phenom, photos of the Velella velella are popping up all over Twitter, making us long for the beach and for some more knowledge on our way cool ocean.

Here are the best of those Twitter photos. But perhaps look at them after you've left the office, okay? Otherwise you'll be wishing for that cool ocean breeze, and are likely to find yourself playing hooky on some wild goose chase for Velella.